Carriers that count                                                                           An exactly solvable model for superconductivity includes two crucial features of the cuprates and sheds light on unexplained experiments. Nature Physics, Jul. 2020



meissnerParadox in superconductivity at high temperature Superconductivity is a bizarre but useful physical phenomenon. Nature publishes an article on a paradoxical discovery in superconductivity. Leiden physicist Jan Zaanen writes a News & Views article about this in the same issue of August 19th. Nature, Vol.536,


Electrons go with the flow in exotic material systems ecotic electrons

Science Vol. 351, 2016 


High temperature superconductivity: Electron mirages in an iron salt                  The detection of unusual ‘mirage’ energy bands in photoemission spectra of single-atom layers of iron selenide reveals the probable cause of high-temperature superconductivity in these artificial structures. Nature Vol. 515, 2014


hidden orderThe sound of a hidden order                                       Ultrasound measurements in a copper oxide superconductor have revealed an exotic phase of matter, composed of loops of spontaneous quantum currents, that has hitherto excelled at evading observation. Nature, Vol. 498, June 2013


Holographic duality: Stealing dimensions from metals                                  Although electrically charged black holes seem remote from superconductors and strange metals in the laboratory, they might be intimately related by the holographic dualities discovered in string theory. Nature Physics Vol.9, Aug 2013


the secret of the hourglassThe secret of the hourglass                                                       The finding that a cobalt oxide insulator’s magnetism is similar to that of cuprate superconductors lends support to the popular but contentious idea that stripe-like electronic order is present in the latter materials. Nature Vol. 471, 2011



The benefit of fractal dirt                                                                                 Measurements of X-ray diffraction on small patches of a copper oxide superconductor reveal that oxygen crystal defects form fractal structures that seem to promote high-temperature superconductivity. Nature Vol. 466, 2010


Journalclub: quantum criticality versus string theory                                                A theoretical physicist journeys to a hairy black hole’s horizon. Nature Vol. 462, 2009


knotsFast Electrons Tie Quantum  Knots                                Special relativity and quantum physics combine to generate unusual arrangements of electron spins in two different solids. Science Vol. 323, 2009



The pnictide code                                                                                                                 Hopes are that the emergent family of iron-based superconductors, the pnictides, could act as a Rosetta stone in decoding the two-decade mystery of superconductivity observed at high temperatures. Prof. Zaanen comments in Nature Vol. 457, 2009


scienceQuantum Critical Electron Systems: The Uncharted Sign worlds                                                                                        This perspective by Prof. Zaanen addresses the Fermion sign problem and describes experiments on metals undergoing quantum phase transitions exhibiting scale-invariant electronic behavior, a description of which is at odds with established quantum theory. Science Vol. 319, 2008


black holeA black hole full of answers                                                         A facet of string theory, the currently favoured route to a ‘theory of everything’, might help to explain some properties of exotic matter phases —such as some peculiarities of high-temperature superconductors. Nature Vol. 448, 2007



rushhourWatching Rush Hour in the World of Electrons               An improved imaging technique reveals that electrons in a material can suffer gridlock like cars in a city. This may help researchers understand the mechanism by which currents flow without resistance in superconductors. Science Vol. 315, 2007



superconductivityQuantum stripe search                                                                Do quantum stripes exist or not? Further indirect evidence for this controversial behaviour of electrons in high-temperature superconductors comes from measurements of atomic-lattice vibrations. Nature Vol. 440, 2006


technology meets quantum criticality1Technology meets quantum criticality        Superconductivity and antiferromagnetism are in fi erce competition in high temperature superconductors. However, this competition has the unexpected benefit that the antiferromagnetism improves the capacity of the superconductormagnetic fields. Nature Materials Vol. 4, 2005


Journalclub: Penrosian gravitational wavefunction collapse                                      Prof. Zaanen comments in a journal club  on the The Road to Reality in which the distinguished mathematical physicist Roger Penrose argues that the limit of quantum rules is rooted in a physicist’s nightmare: the deep conflict between quantum mechanics and Einstein’s general theory of relativity. Nature Vol.436, 2005


why the temperature is highWhy the temperature is high                                         According to a new empirical law, the transition temperature to superconductivity is high in copper oxides because their metallic states are as viscous as is permitted by the laws of quantum physics. Nature Vol. 430, 2004



stripes defeat the fermi liquids Stripes defeat the Fermi liquid                                                    Prof. Zaanen wrote a comment about the mysterie of High-temperature superconductivity. Nature Vol. 404, 2004




pebbles in the nodal pondPebbles in the nodal pond                                                 Rippling patterns of electron waves in a copper oxide match the expectation for a certain kind of excitation — another step towards understanding why copper oxides superconduct at far higher temperatures than other materials. Nature Vol. 422, 2003



Quantum salad dressing                                                                                                            The mystery of how electrons in a high-temperature superconductor flow without resistance grows deeper. New pictures at the atomic scale reveal  two electronic phases that — like oil and vinegar — do not easily mix. Nature Vol. 415, 2002



Self-Organized One Dimensionality                                        Prof. Zaanen reports on some unusual electronic properties of fully developed stripes, providing novel clues on the physics behind superconductivity. Science, Vol 286  1999







































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